Interpretation Made Easy

LEAD PLACEMENTLIMB LEADS MUST BE PLACED ON THE

LIMBSUses both positive and negative electrodesCurrent towards positive, view from negative

Precordial Leads

Acquisition & Transmission

Acquisition & TransmissionSkin Preparation

Helps obtain a strong signalSkin oils reduce adhesion of electrode

and hinder penetration of electrode gelDead, dried skin cells do not conduct

well

Acquisition & Transmission

Rubbing skin with a

gauzepad can

reduce skin oil

and remove some of

dead skin cells

Acquisition & TransmissionOther causes of artifact

Patient movement

Cable movement

Vehicle movement

Electromagnetic Interference (EMI)

Acquisition & TransmissionPatient Movement

Make patient as comfortable as possible Supine preferred

Look for subtle movement toe tapping, shivering

Look for muscle tension hand grasping rail, head raised to

“watch”

Acquisition & TransmissionCable Movement

Enough “slack” in cables to avoid tugging on the electrodes

Many cables have clip that can attach to patient’s clothes or bed sheet

Acquisition & TransmissionElectromagnetic Interference (EMI)

Can interfere with electronic equipment60 cycle interference is a type of EMILook for nearby cell phones, radios or

electrical devicesNo contact between cables & power

cordsTurn off or move away from AC devicesUse shielded cables; inspect for cracks

Limb Lead PlacementTraditional Placement

Acceptable Placement

Avoid placing on the trunk!!!

Chest Lead PlacementV1: fourth intercostal space

to right of sternumV2: fourth intercostal space

to left of sternumV3: directly between leads

V2 and V4V4: fifth intercostal space at

left midclavicular lineV5: level with V4 at left

anterior axillary lineV6: level with V5 at left

midaxillary line

Acquisition & TransmissionThings to look for

Little or no artifactSteady baseline

Acquisition & Transmission

12-Lead ValidationLead I – Global Negativity?

P, QRS and T Wave inverted?R Wave Progression?

R Wave size increases in V leadsTransition Zone?

R Wave should be predominately positive in V3 and V4

12-Lead ValidationLimb leadsP wave, QRS, and

T wave upside down in Lead I

Global negativityUpper limb leads

switched

12-Lead ValidationR wave

progressionR waves progress

in size from V1 to V4

If poor progression, check lead placement on electrodes

normal poor